Bone conduction audiphone



Jan. 17, 19,39.

H.v KocH BONE CONDUCTION AUDIPHONE Filed Aug. '514, 1935 .i4 if .f6 INVENOR. HemyKaeh,

wg I msavAToRNE r Rossem Patented Jan. 17, 1939 UNiTED s'rlx'rlssv aus 71945 BoNE coNnUo'rroN AUnrPnoNn Henry Koch, Jamaica, N. Y., assigner yto Dictograph Products Company, Inc., New York, N. Y., a corporation oi' Delaware Application August 31, 1935 Serial N o. 38,682

"z claims. (cl. 179-107) This invention relates to audiphones and has particular reference to audiphone receivers having a vibrating element adapted to be placed in operative connection with the bone structureel' .5 the user'for transmitting audible sounds picked up by a suitable microphone to the inner ear through the bone structure.

-In copending application Serial No. 678,130, filed June 29, 1933, there is disclosed a bone conduction receiver which is characteristic in that the electromagnetic means of the receiver is supported by the tympanum or reed, so that, in response to energization byv voice currents, the

inertia of the electromagnetic means causes it l5 to' in effect remain stationary while the tympanum or reed vibrates relatively thereto. The casing of the' receiver is secured to the tympanum Aor reed and consequently vibrates over its'entire surface, so that any portion thereof may be supported by a head-band or other holder inopera-v tive connection with the bone structure of the user, such as on the mastoid eminence, for transmitting its vibrations therethrough. This device has proven eminently satisfactory,

but because the surface area of the casing wall which engages the bone is relatively large, a considerable amount of power is required to produce suilciently strong vibrations to enable the user to hear well. In this respect the so-called button type of bone conduction receiver, in which a button carried by the tympanum or reed en' i y of the magnetic gap.

InA 'accordance with one form of the present invention, a bone conduction receiver is provided Ain which the advantages of the button type re ceiver, in so far as concentrated vibration and reduced power-consumption are concerned, are

` combined with the advantages of the reaction or inertia type bone receiver, in so `far as practicability and operating effectiveness are concerned. The aforementioned form of the invention has several modifications, one of which comprises an electromagnetic means supported by its tympanum or reed on the face plate of a casing adapted tobe supported by a headband or the like in position for operative connection with the bone structure of the user, and having a button extending through the face plate and connected to the electromagnetic means so that the receiver casing, due to the inertia of the electromagnetic means, vibrates as a unit and-at the same time the button concentrates a portion of the vibrations. In this way, the face plate engages a 10 relatively large area of the bone and the button engages Aa relatively small area of the bone, and the instrument combines the advantages of the button and inertia 'or reaction type of bone receiver without having the disadvantages of these 15 two types of devices. The electromagnetic means is preferably of the cantilever type with the button located adjacentl the fulcrum, to produce powerful button vibrations of small amplitude.

Another modification of the invention com- 20 prises a casing supported by a headband or other holder and having the electromagnetic means secured thereto in such a way that the tympanum or reed vibrates freely therein without producing a reaction suflicient'to materially vibrate the cas` 25 ing, because the inertia of the reed is relatively low. Secured to this tympanum or reed is a button projecting through the face plate of the casing for operative connection with the bone structure of the user, the tympanum or reed being 30 stiff and substantially unaffected by any pressure which isy applied to the button by contact between it and the bone structure ofthe user. In this form, the so-called button eiiect predominates, as compared to the inertia or reaction 35 eilect. In another form of the invention, the electromagnetic means is secured to the casing, which is supported by the headband, while the contactor, adapted to operatively engage the bone 40 structure'of the user, is secured to the tympanum orl reed, so that the reaction effect is relatively vsmall because. the inertia of the tympanum or the whole casing is not vibrated and hence it is not necessary to vibrate the headband. Resilient means is preferably interposed between the cas- 55 'Ihis form of the invention is, in 45v ing and the vibrating contacto: or face plate, whereby contact between the reed and the pole piece is prevented in case of undue pressure on the face plate, without any reduction in etfectiveness of the vibration thereof.

It will be seen that with the several :forms of this invention, the advantages of the button and inertia reaction types of bone conduction receivers are combined with the result that a more ecient and more eiective instrument is produced.

For a more complete understanding of theinvention reference may be had to the accompanying drawing, in which:

Figure 1 illustrates the new bone conduction receiver of this invention, supported on the headband and connected in a microphone circuit;

Fig. 2 is an enlarged longitudinal section through the receiver of Fig. 1;

Fig. 3 is an enlarged longitudinal section through a modined iorm of the receiver of Fig. 2; and

' Figs. 4, 5 and 6 are enlarged longitudinal sections through other niodilcations of the invention.

Referring to Fig. l, the bone conduction receiver A includes a casing I0. ci' hardrubber, phenolic resin, or the like, having a face plate II with a button I2 projecting slightly beyond the latter, and with opposite surface slots i3 in which the prongs It of the' fork I 5 of the headband IB, or other holder, are pivotally inserted. An electric cord Il, connectible with separable electric connectors i8 to the electromagnetic means within the casing I, includes two wires I9, connected in the circuit oi the battery 20 and the microphone 2|. Suitable amplifying means, not shown, may-be provided. The receiver A is adapted to be placed withits button I2 and face plate il simultaneously in operative contact with the bone structure oi the user, such as on the mastoid eminence behind' the ear, with a headgend I8 supporting the receiver A in that posion. r

As is illustrated in Fig. 2, the tympanum or reed 22 is secured rigidly by screws 23, or the like, to the inner surface of. the face plate Ii. One end, 2t, ci this reed 22, is turned upwardly and supports cantilever-fashion the elongated bar magnet 25 having at its free end the pole piece 28, the end of 'which is spaced from the corresponding surface of the reed 22 to form a narrow air gap. The speech coil 21 may be carried by the pole piece 23, and its terminals are connected by two illamentary conductors 23 toA Figs. 1 and 2. The degree of projection of the button I2 beyond the surface of the face plate i! may be adjusted by screwing stem 33 in or out of the bar magnet 25 and locking it in ad- `lusted position by means oi lock nut 3d.

In operation, the bone conduction receiver A,

4 illustratedk in Fig. 2 is supported by a headband I 6, or the like, in the manner -shown in Fig. 1, so that the face plate Ii and the button i 2 are slmultaneouslyin operative contact with the bone of Figs. l and 2.

aisance structure ci the user, such as the mastoid eminence. Because the inertia oi Y the magnetic structure, including the magnet 25, the pole piece 2E and the speech coil 21, is considerably greater than the inertia of the reed 22 and its appurte- ,5 nant parts, the vibration eected by the electromagnetic means in responsev to voice currents, causes this magnetic structure in effect to remain stationary while'the reed 22 -and the casing I0, Ii vibrate as a unit, thus transmitting their vibrations through the bone structure to the inner ear of the user.

The relative vibrations between the reed 22 and the magnetic structure are utilized in this receiver by means of the button I2, which is 1;, carried by thelxnagnetic structure and thus transmits concentrated vibrations through the bone structure of the user. The spacing of the button l2 from the fulcruin of the cantilever magnetic structure carrying it. causes the button I2 to produce powerful vibrations of small amplitude, whereby power requirements are reduced. Accordingly, the receiver illustrated in Fig. 2 combines the advantages of the button and inertia or reaction type receivers, operating in the characteristic fashion of each ofthem without embodying their disadvantages.

The receiver illustrated in Fig. 3 is a inodication of the receiver of Fig. 2 in that the bar magnet 35 is supported by a spring strip 36 on the reed 3l, which alsocarries a stiicantilever spring 38, with respect to which the bar magnet- 35 and consequently the airgap is adjustable by means of the stem 39 and nuts dil interconnecting spring 3B and the bar magnet 35. The advantages oi adjustability of the air gap and the avoidance of fatigue of the vibrating metal bythis spring structure are discussedin greater detail in my copending application Serial No. 733,739, filed July 5, 1934 which discloses the structure of Fig. 3 just described. l

In addition to aording a means for adjustment of the air gap and the likestem 39 also carries the button I2' and is adjustable axially in the bar magnet to vary the degree oi projection oi? the button I2', which is locked in adjusted position by lock nut 4I. The operation of the form illustrated in Fig. 3 is the same as that described in connection with'the arrangement In the modification illustrated in Fig. 4, the

bar magnet i2 is rigidly secured to the back of the casing d3 by means of screws d, so that the reed l5 extends parallel to the inner surface oi the face platell and is free to vibrate relatively thereto in response to energization of the electromagnet means by voice currents. Because the inertia of the reed B5 is small compared to I the inertia of the magnetic structure including the bar magnet 42, thel pole piece 61 and the 60 voice coil d8, together with the casing 53 and face plate 46, the reaction eiect is relatively small, although, by increasing the mass of the reed 45, the reaction effect maybe increased at will.

Threaded through reed 65 is a stem 49 car- Arying the button I2." projecting through face plate 4B and forming a relatively small proportion ci the total surface area of the latter. 'I'he degree of projection of button I2 beyond the 70 surface of face plate t may be varied by screwing stem 9 inwardly or outwardly through reed 45 and locking it in adjusted position by means of lock nut 59'. In this arrangement, practithe projection' of the button I2" slight, so that there is no suppression of the vibration of the reed 45 by contact of button I2" With the bone. The degree of vibration of the casing 43 may be varied by increasing or decreasing. the mass of the reed 45 and button I2". For example, by increasing their mass the reaction effect is increased.

In the form of the invention illustrated in Fig. 5, the bar magnet I is rigidly secured by screws 52 to the casing 53, while the reed 54 is rigidly secured by screws 55 to the face plate 56. The face plate 56 and the cooperating surface of casing 53 are spaced apart to permit relative vibration between them and this space is iilled by a gasket 51 of soft'rubber, felt,'or other cushioning material. 'Ihe face plate 56 is, in eect, a button, the' area ofwhich is the entire arca of face plate`56.

Energization of the speech coil 58 in accordance with voice currents, causes reed 54 and face plate 56 to vibrate relatively to the headbandsupported casing 53, so that its vibrations are transmitted to the inner ear through the bone structure and little' or no vibration is :imparted to the headband. The gasket v51 is sufliciently rm to prevent substantial suppression of the vibration of the reed 54 because of its contact with the head, and also prevents contact or freezing between the pole piece 59 and the reed 54, as well as preventing access of dirt into the casing 53,

Alternatively, the arrangement of Fig. 5 may g be modied as illustrated in Fig. 6 by inserting the face plate 60 Within the opening of the casing 6I, so that the plate 60 forms a large proportion of 'the area of the corresponding wall of the receiver. As the reed 62 carrylngthe face plate 60 is vibrated by the electromagnetic means, including the bar magnet 63, the pole piece 64 and the speech coil 65, all carried by the casing 6I the vibrations of the reed 6 2are transmitted by face plate l6I) through the bone structure to the inner ear of the user,

Although the reeds 22 and 31 of the forms shownV in Figs. 2 and 3 are supported by the headband I6, inasmuch as the latter is connected to the casing IIJ, II to which the reeds 22 and 31 are secured,vthese instruments may be supported by their electromagnetic means, if desired, simply by connecting the headband to the bar magnet and 35, or the like, through suitable openings in the wall of casing I0. Similarly, although the electromagnetic means is supported by the headband in Figs. 4, v5 and 6, inasmuch as the latter is connected to the casings 43, 53 and 6I, these instruments may be supported by their reeds by connecting the headband thereto, either directly or to the face plates 56 and 60 in Figs. 5 and 6. 'I'he effect of this change of support would be to convert the forms of Figs. 2 and 3 into so-called button type bone receivers and the forms of Figs. 4, 5 and' into inertia or reaction type receivers.

While several preferred embodiments of the invention have been illustrated and described herein, it is to be understood that the invention ,is not limited thereby but is susceptible to changes in form and detail within its scope.

I claim: 1. In an audiphone, the combination of elec tromagnetic means adapted to respond to vary.-

3 ing currents substantially throughout the audible frequency range, a casing secured thereto, a relatively stif vibratory member connected to the means for vibration thereby, a contactor secured to the member and movable relatively to the casing and forming at least a major part of a wall of the casing, and means supporting the casing with the/contactor inoperative contact with the bone structure of the user for conducting its vibrations therethrough to the inner ear.

2. In an audiphone, the combination of electromagnetic meansadapted to respond to varying currents substantially throughout the audible frequency range, al casing secured thereto, a relatively stif vibratory-member operatively associated with the means for vibration thereby, a contactor connected to the member and forming at least part of a wall of the casing, resilient means between the contactor and thecasing whereby the contactor can vibrate relatively to the casing, and means supporting the casing with the contactor in operative contact with the bone structure of the user for conducting its vibrations therethrough to the inner ear.

3. In an audiphone, the combination of a casing, vibratory means in the casing comprising two members having unequal inertias resiliently associated for limited relative movement between at least portions of both members, means securing one of said members to the casing, electromagnetic means adapted to respond to varying currents substantially throughout the audible frequency range secured to said portion of one of said members and operatively opposed to said portion of the other member for relatively vibrating the same, a contactor forming at least part of a wall of the casing connected to the unsecured member for movement relatively to the casing in accordance with said vibration, and means supporting said casing with said contactor in operative contact with the bone structure of the user for'conducting its vibrations 'therethrough to the inner ear.

4. In an audiphone, the combination of a casing, vibrator means in the casing comprising two vmembers having unequal inertias resiliently associated for limited relative movement between at least portions of both members, means securing the member having greater'inertia to the casing, electromagnetic means adapted to respond to varying currents substantially throughout the audible frequency range secured to said portion of one of said members and operatively opposed to said portion of the other member for relatively vibrating the same, a contactor forming at least part of a wall of the casing connected to the unsecured member ior movement relatively to the casing in accordance with said vibration, and means supporting said casing with said contactor in operative contact with the bone structure of the user for conducting its vibrations therethrough to the' inner ear.

v5. In an audiphone, the combination of a casing, vibratory means in the casing comprising two members having unequal inertias resilientlyv associated for limited relative movement between at least portio'ns of both members, means securing the member having greater inertia to the casing, electromagnetic means adapted to respond to varying currents substantially throughout the audible frequency range secured to said portion of one of said members and operatively opposed'to said portion of the other member for relatively vibrating the same, a contactor forming at least a major portion of a wall of the ing its vibrations therethrough to the inner ear.

casing connected to the unsecured member for movement relatively to the casing in accordance with said vibration, and means. supporting said casing with said contacter in operative contact with the bone structure of the user for conduct- 6. In an audiphone, the combination of electromagnetic means adapted to respond to varying currents substantially throughout the audible frequency range, a casing secured thereto, a relatively stif vibratory member connected to the,

aisance for conducting its vibrations therethrough to the inner ear.

7. In an audiphone, the combination of electromagnetic means adapted to respond to varying currents substantially throughout the audible frequency range, a casing secured thereto, a relatively sti vibratory member connected to the means for vibration thereby, a contacter secured to the member and movable relatively to the casing and forming at least the major part of a Wall of the casing, resilient means interposed between the contactor and a xed part ofthe audiphone for limiting the movement of the contacter relatively to the casing, and means supporting the casing with the contacter in operative contact with the bone structure of the user for conducting its vibrations therethroughto the inner ear.

may KOCH. 

